Rotor position estimation device, motor control device, and recording medium

A motor control device comprising:

• an inverter that drives a three-phase alternating current motor;
• a current difference detection circuit that detects a difference in current between first detection timing and second detection timing in at least one phase of three phases of the three-phase alternating current motor;
• a detection timing generation circuit that generates the first detection timing and the second detection timing such that a current flowing in a first direction by application of a power supply voltage and a current flowing in a second direction by application of the power supply voltage can be canceled in the phase to be detected in the current difference detection circuit;
• a position estimation circuit that estimates the rotational position of the rotor on the basis of a zero crossing point of the difference in current;
• and
• a PWM generation circuit that generates a signal for controlling the inverter on the basis of an estimation result of the rotational position of the rotor.

A non-transitory computer readable recording medium recording a program for causing a computer to control a rotor position estimation device used for a motor drive circuit that drives a three-phase alternating current motor by an inverter, and which estimates a rotational position of a rotor of the three-phase alternating current motor, the program for causing the computer to function as:

• a unit that detects a difference in current between first detection timing and second detection timing in at least one phase of three phases of the three-phase alternating current motor;
• a unit that generates the first detection timing and the second detection timing such that a current flowing in a first direction by application of a power supply voltage and a current flowing in a second direction by application of the power supply voltage can be canceled in the phase to be detected in the unit that detects a difference in current;
• and
• a unit that estimates the rotational position of the rotor on the basis of a zero crossing point of the difference in current.